台式能量色散X射线荧光光谱直接检测大米中的Cd

Direct Determination of Cadmium in Rice by Bench-Top Energy Dispersive X-ray Fluorescence Spectrometer

建立一种基于台式能量色散型X射线荧光光谱对大米中重金属Cd的快速、直接测定方法。针对普通能量色散X射线荧光光谱灵敏度低的问题,通过X射线荧光光谱理论分析并结合样品杯试验提高Cd的信噪比,通过对谱图中逃逸峰的对比分析排除其对Cd信号的干扰。本方法操作简单,不需要对大米样品进行前处理,可直接对大米进行检测;本方法的相对标准偏差小于10%,检出限达到0.054 mg/kg,实验中所使用的工作曲线的测定线性范围为0.06~1.0 mg/kg,单一样品检测时间为18 min左右,实际样品测试结果同电感耦合等离子质谱法结果一致,能够满足现场快速、准确、无损测定大米中Cd含量的要求,可为大米中Cd是否超标提供一种快速筛查方法。

This study established a rapid, direct measurement method for cadmium(Cd) in rice using a bench-top energy dispersive X-ray fluorescence spectrometer. Due to the low sensitivity of ordinary energy dispersive X-ray fluorescence spectrometer, this research work was focused on improving the signal-to-noise ratio of Cd by combination of X-ray fluorescence spectroscopic theoretical analysis and sample cup experiments. At the same time, interference signals of escape peaks have been eliminated. This method allowed direct detection of cadmium in 18 min without any sample pre-treatments, and with RSD below 10% and a detection limit of 0.054 mg/kg, and the linear range of the working curve was from 0.06 to 1.0 mg/kg. Consistent results were obtained for real rice samples in comparison with inductively coupled plasma mass spectrometry(ICP-MS). It has been proved as a rapid screening method for Cd in rice on site.